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11 Cards in this Set
- Front
- Back
Reproduction System- Stem Cell Therapy by Thatcher
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Reproduction System- Stem Cell Therapy by Thatcher
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Recognize strategies for treating genetic disorders, and list examples of diseases treated by different strategies
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in some packet.
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Discuss principles for providing appropriate genetic counceling
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1.consult patient
2. perform risk assessments (eg., family history) 3. testing 4. treatment 5. consult patient (informed consent, confidentiality) *non-directive- don't tell what to do, just give the information. |
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Recognize what GINA does and does not cover
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GINA (Genetic Information Non-Discrimination Act)
Prohibits health insurers from using genetic information in determining eligibility or setting premiums Prohibits employers from purchasing a person’s genetic information, or using genetic information in decisions regarding hiring, firing, work assignments, etc. Prohibits health insurers or employers from requesting or requiring a person or family member to undergo a genetic test *can't use genetic information against you. not required to take genetics test. *does NOT cover life insurance, medical underwriting, apply to military personnel, prevent physicians from ordering genetic tests, mandate coverage for specific genetic testing or tx. |
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List advantages and limitation of different strategies for gene therapy.
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Germ Line Transformation: replace a mutant gene with a wild type allele in the germ line (added to blast cells, eggs or sperm); can eliminate the defective gene; Microinjection, Homologous recombination; Experimental tool, e.g. gene knockout mice
Somatic Transformation: deliver a wild type gene to somatic cells of an adult or child, without eliminating the mutant allele; All current trials In vivo- transformation of cells within the body Ex vivo- transformation of extracted cells, which are then reimplanted back into the body. Direct: Gene Replacement: add wild type gene to cells with mutant genes RNAi (inhibits): inhibits expression of specific gene Indirect (most target cancerous cells): Suicide genes: toxic genes, expression often activated by prodrug Immune Response: antigenic genes, transformed cells cleared |
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List challenges for developing effective gene therapies
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-Transformation Level (non-dividing cells difficult)
-Expression Level -Regulation (correct spacial, temporal, stimuli responsive expression) -Targeting Specific Organ or Cell Type -Transformation Stability (biggest problem) --Chromosomal Integration --Immunogenicity (transformed cells cleared, often increases with repeated treatments) Multifactoral traits: transforming patients with multiple transgenes is impractical, but it may be reasonable to treat specific diseases by transforming patients with one or a few critical genes) Gene size: large genes more difficult. |
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Discuss the advantages and disadvantages of using viral vectors for gene therapy, and the advantages and disadvantages specific to the three major viral vectors.
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Naturally Infect Host Cells; Cell Type Specificity; Genetic Engineering
(Replication defective; Restricts gene size) Chromosomal Integration (Retroviruses): Transformation stable; Transformation propagated in daughter cells; Insertional mutagenesis; Chromosomal integration (stable transformation transformation propagated in daughters; insertional mutagenesis); require a dividing cell, limited transcript size Extrachromosomal Replication (Adenoviruses): Transient transformation; No risk of insertional mutagenesis; DNA viruses; wide range of targets; don't require cell division; accommodate larger genes (8-30kb); transient transformation; immunogenic Adeno-Associated Viruses: require adenovirus co-infection; target brain and muscle; small capacity (about 5kb) |
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Describe methods for hematopoietic transplantation stem cell therapy
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Viral Infection- can genetically engineer them
Lipofection - package vector in membranous vesicles Condensed DNA Particles - package vector in protein coat Molecular Conjugates - bind DNA to ligand, usually protein Naked DNA Injection - inject DNA directly into solid structures (e.g. tumors, muscles) Electroporation - run an electric current through cells ex vivo or dermal Gene Gun - shoot gold particles coated with DNA into cells with a high-pressure helium stream . ex vivo or dermal |
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List challenges for developing effective stem cell therapies
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Seed Threshold- stem cell quantity must be high enough for graft to take
Cell culture expansion- premature differentiation needs to be controlled. Controlling differentiation- growth factors to prevent premature differentiation and control differentiation. Immunogenic rejection- body recognizes as foreign, the stem cells are eliminated as you put them in. Autologous- patient's own cells; no rejection. Allogeneic- cell from a matched donor. Infection- Development of secondary cancer- |
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Describe the advantages and disadvantages of adult and embryonic stem cell therapies
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Adult stem cells: mesenchymal; undifferentiated (more differentiated than embryonic stem cells)
Embryonic stem cells: isolated from inner cell mass of a blastocyst; pluripotent (less differentiated than adult stem cells); ethical issues |
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Name some dangers with gene therapy
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Immune Responses: when immunocompromised, systemic immunologic reaction ex anaphylactic shock
Horizontal Transformation: from transformed cells to another cell type that should not be transformed, e.g. from somatic to germ line cells Pathogenic Vector Development: inadvertently creating a new pathogen e.g. replication competent viral reversion due to mutations Insertional Mutagenesis: (XSCIDS case) ; gene inserting into another gene. the virus may carry regulatory sequences with it. |